Contrast ratio results for iMac 21"

Contrast ratio 2977:1
Monitor model iMac 21"
Submitted 01 Sep 2011 20:16 CEST, by 85.180.*.*
Camera model Nikon D40
Processing remarks

Warning: image file 1: Underexposed. Please increase the shutter time.
Note: image file 1: suggested exposure time: 13.9 s (Set EV to +3.8)

Black
Screen photo
Luminance 0.03 cd/m2
Luminance spread 0.02 cd/m2 (2 standard deviations)
Exposure value –6.3 stops   (aim for –2 to –3)
Exposure spread 0.79 stops
Area used for calculation 0.375 x 0.423
Camera settings Exposure time: 1   ISO: 400   F-number: 3.5
Focal length: 27 mm   (35 mm equivalent)
Exposure compensation: 0
White
Screen photo
Luminance 99 cd/m2
Luminance spread 9 cd/m2 (2 standard deviations)
Exposure value –2.4 stops   (aim for –2 to –3)
Exposure spread 0.14 stops
Area used for calculation 0.375 x 0.423
Camera settings Exposure time: 1/200   ISO: 400   F-number: 3.5
Focal length: 27 mm   (35 mm equivalent)
Exposure compensation: 0

The luminance values in cd/m2 are not very reliable, since camera sensitivities can easily differ up to 50% from their nominal value. Typically, the real luminance is 30% lower than this number. The area used for calculation is chosen such that it corresponds to a viewing angle of ±14° horizontally and ±10.5° vertically, which is equivalent to viewing the screen from a distance of about 1.5 times the diagonal size.

Unfortunately, there is a lot of variation in how cameras use EXIF settings. If photos from your camera your produce unusable results, try coming back in a few days. I review submitted pictures regularly and try to fix problems.